Acylation Process

ABSTRACT

The invention concerns a process for the manufacture of an acylated polymer composition comprising amylose and/or amylopectin, comprising a pre-treatment step in the presence of an acid, and optionally one additive selected from the group of a hydroxycarboxylic acid and a salt in combination with a polycarboxylic acid. After pre-treatment, the polymer is acylated and, preferably, subjected to a post-treatment step with an acid. The products obtained are useful as additives in varnishes, lacquers, coatings, thickeners, adhesives or binders, and preferably inks.

This application claims priority to European application No. EP13188992.5, the whole content of this application being incorporatedherein by reference for all purposes.

The present invention relates to an acylation process of polymercompositions comprising amylose and/or amylopectin, acylated polymercompositions comprising amylose and/or amylopectin products and the useof such acylated products in certain applications, preferably in inks.

Acylated polymer compositions, like acetylated starch, are importantprocessed renewable raw materials which can be used in a wide range ofindustrially applied polymers. They can be applied for example in inks(e.g. WO2012059), excipients in pharmaceutics (e.g. WO11011217) andfoodstuffs (e.g. US2013236624).

A common process for the acylation of polymer compositions comprisingamylose and/or amylopectin, such as starch, is the reaction of such apolymer composition with an acetylating agent, for example a carboxylicacid anhydride, which reacts with the hydroxylfunctions of the polymerto form the acylated polymer composition. The physical properties of theacylated polymer composition, specifically acylated starch, aredifficult to control in the acylation process. It is therefore an objectof the present invention to provide an improved process for theacylation of polymer compositions comprising amylose and/or amylopectin,such as starch. An acylated polymer composition comprising amyloseand/or amylopectin with superior physical properties is another objectof the present invention. It is also the object of the present inventionto provide a process for the manufacture of inks, varnishes, lacquers,coatings, thickeners, adhesives or binders using the acylated polymercomposition comprising amylose and/or amylopectin with superior physicalproperties as ingredient. Preferably, these acylated polymercompositions are used as ingredient in the manufacture of inks.

It was now found that the physical properties of acylated polymercompositions, such as acylated starch, may effectively be controlled bytreating the starch before with an aqueous phase comprising one additiveselected from the group consisting of at least one acid A having a pKaof equal to or less than 4.8 at 25° C. and an enzyme, and optionally oneor more additives selected from the group comprising at least one saltin combination with at least one polycarboxylic acid, and at least onehydroxycarboxylic acid. The physical properties can further becontrolled in an additional step after the acylation step, by treatingthe acylated polymer with at least one acid A′ with a pKa of equal to orless than 4.8 at 25° C., in the presence of water.

Consequently, in its broadest embodiment, the invention concerns aprocess for the manufacture of an acylated polymer composition having aviscosity between 10 to 200 mPas (35 w % in EtOAc at 25° C.) whichcomprises

(a) pre-treating a polymer composition comprising amylose and/oramylopectin with an aqueous phase comprising one additive selected fromthe group consisting of at least one acid A having a pKa of equal to orless than 4.8 at 25° C. and an enzyme, and optionally one or moreadditives selected from the group comprising at least one salt incombination with at least one polycarboxylic acid, and at least onehydroxycarboxylic acid,(b) reacting the pre-treated polymer composition with an acylating agentto provide an acylated polymer composition comprising amylose and/oramylopectin.

The pre-treatment step in the process allows for efficient swelling ofthe polymer composition, therefore providing pre-treated polymer whichcan be efficiently acylated. Additionally, adjustment of the viscositycan be effected in the pre-treatment step. This is further detailedbelow. Preferred polymer compositions comprising amylose and/oramylopectin are starches.

In a preferred embodiment, the invention concerns a process for themanufacture of an acylated polymer composition comprising amylose and/oramylopectin having a viscosity from between 10 to 200 mPas (35 w % inEtOAc at 25° C.) which comprises

(a) pre-treating a polymer composition comprising amylose and/oramylopectin with an aqueous phase comprising one additive selected fromthe group consisting of at least one acid A having a pKa of equal to orless than 4.8 at 25° C. and an enzyme, and optionally one or moreadditives selected from the group comprising at least one salt incombination with at least one polycarboxylic acid, and at least onehydroxycarboxylic acid,

(b) reacting the pre-treated polymer composition with an acylating agentto provide an acylated polymer composition comprising amylose and/oramylopectin.

(c) reacting the acylated polymer composition obtained in step (b) withat least one acid A′ with a pKa of equal to or less than 4.8 at 25° C.,in the presence of water.

In step (c) according to the process in of the preferred embodiment, apartial hydrolysis takes place, by which the DS controlled. Theresulting products have an improved EtOH tolerance. DS and EtOHtolerance are explained further below.

The invention further concerns an acylated polymer compositioncomprising amylose and/or amylopectin, which is obtainable by such aprocess.

Another object of the invention is an acylated polymer compositioncomprising amylose and/or amylopectin, having a degree of substitution(DS) in the range of from 2.0 to 2.9, wherein the viscosity of polymercomposition is from 10 to 200 mPas (35 w % in EtOAc at 25° C.) and whichhas a EtOH tolerance of equal to or lower than 60% (v/v).

A further object of the invention is an acylated polymer compositioncomprising amylose and/or amylopectin, having a degree of substitution(DS) in the range of from 2.0 to 2.9, wherein the viscosity of polymercomposition is from 10 to 200 mPas (35 w % in EtOAc at 25° C.), apolydispersity of 1.3-2.6, a glass transition offset temperature between120-170° C. and a EtOH tolerance of equal to or lower than 60% (v/v).Preferred acylated polymer composition comprising amylose and/oramylopectin are starches.

A process for the manufacture of inks, varnishes, lacquers, coatings,thickeners, adhesives or binders, preferably inks, using acylated starchwhich has been provided by the claimed acylation process, and/or theacylated polymer composition comprising amylose and/or amylopectinobtainable by the claimed process and/or the acylated polymercomposition comprising amylose and/or amylopectin having a degree ofsubstitution (DS) in the range of from 2.0 to 2.9, wherein the viscosityof polymer is from 10 to 200 mPas (measured in a 35 w % in EtOAcsolution at 25° C.) and which has an EtOH tolerance of equal to or lowerthan 60% (v/v), as an ingredient, is also claimed in the presentinvention. EtOH is intended to denote ethanol.

In another aspect, a process for the manufacture of inks, varnishes,lacquers, coatings, thickeners, adhesives or binders, preferably inks,using acylated starch which has been provided by the claimed acylationprocess, and/or the acylated polymer composition comprising amyloseand/or amylopectin obtainable by the claimed process and/or the acylatedpolymer composition comprising amylose and/or amylopectin having adegree of substitution (DS) in the range of from 2.0 to 2.9, wherein theviscosity of polymer is from 10 to 200 mPas (measured in a 35 w % inEtOAc solution at 25° C.), the polydispersity of polymer of 1.3-2.6, theglass transition offset temperature of polymer is between 120-170° C.and which has an EtOH tolerance of equal to or lower than 70% (w/w), asan ingredient, is also claimed in the present invention. In the presentspecification, the plural form and the singular form are usedinterchangeably. Thus, it should be understood that the plural form alsoincludes the singular form and vice-versa, unless otherwise indicatedherein or clearly contradicted by context. For example, “acid” denotes asingle acid or a mixture of two or more acids. As another example,“starch” denotes a single starch from a single source,amylopectin/amylose composition and/or modification as well as a mixtureof two or more starches of different sources, amylopectin/amylosecompositions, modifications etc.

Polymer compositions comprising amylose and/or amylopectin generally canconsist of isolated fractions of amylose or isolated fractions ofamylopectin, or a mixture of amylose and amylopectin. Starch is apreferred polymer composition which comprises essentially a mixture ofamylose and amylopectin. Each of these materials are composed ofD-glucose units linked to one another via α-(1-4) and α-(1-6) linkages,the latter being responsible for the branches in the structure of themolecule. The ratio between the amounts of amylose and amylopectindepends on the source of the polymer, e.g. starch. According to thepresent invention, the starch employed as starting material for theacylation process can comprise predominantly amylose or, conversely,predominantly amylopectin (waxy starch). Generally, whole starch and/orisolated fractions of amylose and/or isolated fractions of amylopectincan be used. According to the present invention, the term “polymercomprising amylose and/or amylopectin” includes its preferred form,namely “starch”. The starches can be derived from any native source,wherein native relates to the fact that said starch is found in nature.Unless specifically distinguished, references to starch in thisspecification are meant to include their corresponding flours, which arestill containing proteins, such as wheat gluten (hereinafter “starch”).In the present invention, a single or several starch sources can beused. The starch may also be combined out of several sources, isolatedamylose fractions and/or amylopectin fractions, and/or derivatives likechemically or physically modified starch, which will be explainedfurther below. Typical sources for the starches are cereals, tubers,roots, legumes, fruit starches and hybrid starches. Suitable sourcesinclude but are not limited to, millet, pea, potato, sweet potato,maize, sorghum, banana, barley, wheat, rice, sago, amaranth, tapioca,arrowroot and cannay. Preferred sources according to the presentinvention are selected from the group consisting of tubers, legumes orcereals. Even more preferably, the starch source is selected from thegroup consisting of pea, potato, sweet potato, wheat and maize. Mostpreferably, maize with a high amylopectin content (waxy maize) is usedas starch source. Also suitable are starches derived from a plantobtained by breeding techniques including crossbreeding, translocation,inversion, transformation or any other method of gene or chromosomeengineering to include variations thereof.

In another embodiment of the present invention, starch is used asstarting material which is chemically and/or physically modified.

“Chemically modified starch” is intended to denote in particular thepartial chemical modification of the hydroxyl-groups in amylose and/oramylopectin.

Generally, chemically modified starches which can be selected asstarting material according to the present invention can be classifiedas crosslinked starches, partially acetylated starches, partiallyetherified starches like hydroxyethylated, hydroxypropylated andmethylated starches, inorganically esterified starches, cationic,anionic (like carboxymethyl starch), oxidized starches, zwitterionicstarches, starches modified by enzymes. The preferred chemicallymodified starch is a partially hydroxypropylated starch.

In one embodiment of the present invention, the modified starch ismaltodextrin. “Physically modified starch” is intended to denote astarch that has been modified by a physical method. Generally, physicalmethods for the modification of starch include heat treatment,heat-moisture treatment, annealing, retrogradation, freezing, mechanicaltreatment, ultra high pressure treatment, gelatinization, glow dischargeplasma treatment and osmotic pressure treatment.

According to the present invention, mixtures of any of the abovementioned starches, modified starches and/or flours, derived from anysource, are also within the scope of this invention. For the sake ofsimplicity, the expression “starch” is intended to denote equally any ofthe starches, modified starches, flours and or/their mixtures, derivedfrom any source with any amylopectin/amylose ratio.

In one embodiment of the invention, the employed starch has an amylosecontent of equal to or greater than 0% and equal to or lower than 60%,based on the sum of weights of amylose and amylopectin. Preferably, theemployed starch has an amylose content of from 0% to 40%. Especiallypreferably, the employed starch has an amylose content of from 0% to20%.

The term “acylation of a polymer composition comprising amylose and/oramylopectin” is intended to denote the reaction of free hydroxylgroupsof the glucose units of a polymer composition comprising amylose and/oramylopectin with an acylating agent to form a corresponding acylatedpolymer composition comprising amylose and/or amylopectin. Principally,polymer composition comprising amylose and/or amylopectin correspond toformula ST(OH)₃ and reacts with a acylating agent to the correspondentacylated polymer composition comprising amylose and/or amylopectin offormula ST(OH)_(3-x)(OC(O)R_(x). “ST” denotes the amylose and/oramylopectin polymer backbone. In the formula ST(OH)_(3-x)(OC(O)R)_(x), xdenotes the DS (degree of substitution) of the hydroxyl groups in thestarch. The DS is the average amount of acylated hydroxyl groups perglucose entity. Generally, the DS of the final acylated polymercomposition comprising amylose and/or amylopectin according to thepresent invention is from 2.0 to 2.9. Preferably, the DS of the finalacylated polymer composition comprising amylose and/or amylopectin isgreater than 2.05. More preferably, the DS of the final acylated polymercomposition comprising amylose and/or amylopectin is equal to or greaterthan 2.07. Most preferably, the DS of the final acylated polymercomposition comprising amylose and/or amylopectin is equal to or greaterthan 2.1. Preferably, the DS of the final acylated polymer compositioncomprising amylose and/or amylopectin is equal to or less than 2.6. Morepreferably, the DS of the final acylated polymer composition comprisingamylose and/or amylopectin is equal to or less than 2.5. Even morepreferably, the DS of the final acylated polymer composition comprisingamylose and/or amylopectin is equal to or less than 2.4. In a mostpreferred embodiment of this invention, the DS of the final acylatedpolymer composition comprising amylose and/or amylopectin is from 2.1 to2.4.

In the case that a partially chemically modified polymer compositioncomprising amylose and/or amylopectin is used, x relates to the freehydroxylgroups of the polymer composition comprising amylose and/oramylopectin. In this case, a modified polymer composition comprisingamylose and/or amylopectin ST(OR^(m))_(z)(OH)(_(3-z)), wherein R^(m) isintended to denote the chemically modifying group of the startingmaterial such as methyl, reacts with an acylating agent to thecorrespondent acylated polymer composition comprising amylose and/oramylopectin of formula ST(OR^(m))_(z)(OH)_((3-z)-x)(OC(O)R)_(x). In thisequation, R^(m) is a chemically modifying group, which, in a firstaspect, does not bear a hydroxylgroup. Thus, in the case that chemicallymodified polymer composition comprising amylose and/or amylopectin isused as starting material, the DS is meant to denote the sum of z and x,DS=x+z. For the sake of simplicity, DS is meant to denote x forchemically not modified starting material or chemically modifiedstarting material when, in a second aspect, R^(m) bears onehydroxylgroup, for example hydroxypropyl, and DS=x+z in chemicallymodified starting material, wherein R^(m) bears not hydroxylgroup,throughout the specification.

According to the present invention, R is an linear or branched aliphaticor cycloaliphatic group containing 1 to 18 carbon atoms, an araliphaticgroup containing 7 to 12 carbon atoms or an aromatic group containing 6to 12 carbon atoms. R can optionally be substituted by one or morehalogens, preferably fluorine, NO₂, phenyl, C(O)OR¹, OR¹ or an aromaticgroup containing to 12 carbon atoms substituted by a C₁₋₆ aliphaticgroup. R¹ is a C₁-C₄ alkyl group, which can optionally be substituted byone or more halogens, preferably fluorine.

An acylating agent is intended to denote a reactant which is capable ofreacting with the hydroxylgroups of the glucose units of a polymercomposition comprising amylose and/or amylopectin, thereby transferringan acyl group —(CO)R, —C(O)R′ and/or —C(O)R″ to form the acylatedpolymer composition comprising amylose and/or amylopectin. Acylatingagents may be, for example, carboxylic acid anhydrides (RC(O))₂O, butalso unsymmetrical carboxylic acid anhydrides corresponding to theformula (RC(O))(R″(O))O. Other suitable acylating agents comprisecarboxylic acid halides or carbonylimidazoles.

According to one embodiment, the polymer composition comprising amyloseand/or amylopectin is pre-treated in step (a) with an aqueous phasecontaining an acid A having a pKa of equal to or less than 4.8 at 25° C.and optionally one or more additives selected from the group comprisingat least one salt in combination with at least one polycarboxylic acid,and one hydroxycarboxylic acid. Generally, the acid A having a pKa ofequal to or less than 4.8 at 25° C. is selected from the groupconsisting of mineral acids, sulfonic acids and carboxylic acids. Theacid A can be either monoprotic or polyprotic. If acid A is polyprotic,at least pKa₁ is equal to or less than 4.8 at 25° C. Preferably, acid Ais selected from the group consisting of sulfuric acid, amidosulfonicacid, methane sulfonic acid, benzene sulfonic acid or phosphoric acid.Most preferably, acid A is selected from the group consisting ofsulfuric acid and benzene sulfonic acid. Generally, more than one acid Acan be present in step (a). In this embodiment, acid A is added in step(a) in an amount of equal to or greater than 0.001 weight %, based onthe amount of polymer composition comprising amylose and/or amylopectin.For this purpose, the weight of any moisture present in the polymercomposition comprising amylose and/or amylopectin before step (a) is nottaken into account when calculating the ratio of acid to polymercomposition comprising amylose and/or amylopectin. If more than one acidA is added in step (a), the sum of weight percentages of the more thanone acids A is the same as the weight percentage denoted in thespecification for a single acid A. Preferably, acid A is added in step(a) in an amount of equal to or greater than 0.01 weight %. Mostpreferably, acid A is added in step (a) in an amount of equal to orgreater than 0.1 weight %. Generally, acid A is added in step (a) in anamount of equal to or less than 5 weight %. Preferably, acid A is addedin step (a) in an amount of equal to or less than 3 weight %. Mostpreferably, acid A is added in step (a) in an amount of equal to or lessthan 1.5 weight %. In a most preferred embodiment of this invention, theamount of acid A added in step (a) is from 0.3 to 1.3 weight %.

In an alternative embodiment of this invention, the amount of acid Aadded in step (a) is from 0.1 to 1.3 weight %.

According to another embodiment, the polymer composition comprisingamylose and/or amylopectin is pre-treated in step (a) with an aqueousphase containing an enzyme and optionally one or more additives selectedfrom the group comprising at least one salt in combination with at leastone polycarboxylic acid, and one hydroxycarboxylic acid. Generally, theenzyme is selected from the group of hydrolases. Preferably, the enzymeis an amylase. The amylase can be of human, animal or plant origin,bacterial source, fungicidal source or genetically engineeredmicroorganism source. Preferably, the amylase is selected from the groupcomprising glucoamylase, α-amylase, β-amylase and γ-amylase. A verypreferred enzyme is the alpha-amylase Termamyl™. The enzyme used asadditive in step (a) is added in an amount equal to or greater than 5 U(enzyme unit) per g polymer composition. Preferably, the enzyme used asadditive in step (a) is added in an amount equal to or greater than 10 U(enzyme unit) per g polymer composition. Even more preferably, theenzyme used as additive in step (a) is added in an amount equal to orgreater than 15 U (enzyme unit) per g polymer composition. Generally,the enzyme used as additive in step (a) is added in an amount equal toor lower than 200 U (enzyme unit) per g polymer composition. Preferably,the enzyme used as additive in step (a) is added in an amount equal toor lower than 150 U (enzyme unit) per g polymer composition. Morepreferably, the enzyme used as additive in step (a) is added in anamount equal to or lower than 100 U (enzyme unit) per g polymercomposition. Most preferably, the enzyme used as additive in step (a) isadded in an amount from 20 to 90 U/g polymer composition. Generally,enzyme degradation in step (a) is stopped by the addition of a 1 to 15%aqueous mineral acid, preferably aqueous hydrochloric acid.

According to one embodiment of the present invention, one or moreadditives from the second group are present in step (a), wherein the oneadditive or one of the two additives is at least one salt and incombination with one polycarboxylic acid. The term “polycarboxylic acid”is intended to denote a carboxylic acid bearing at least two carboxylicacid groups. The polycarboxylic acid comprises from 2 to 12 carbon atomswhich can be substituted, additionally to the at least two carboxylicacid groups, with one or more substituents selected from the groupcomprising primary, secondary or tertiary amines, amides, nitro,nitrile, amido, mercapto, optionally substituted or unsubstituted alkyl,optionally substituted or unsubstituted aryl, keto-group andaldehyde-group. In the case that the optionally substituted orunsubstituted polycarboxylic acid has one or more stereocenters, theterm “polycarboxylic acid” as used in the present invention includes allracemates, enantiomers, diastereomers or mixtures of any of theforegoing. Generally, more than one polycarboxylic acid can be presentin step (a).

Preferably, the polycarboxylic acid of step (a) is selected from thegroup consisting of oxalic acid, malonic acid and succinic acid,glutaric acid and adipic acid. Most preferably, the polycarboxylic acidis malonic acid. In the present embodiment, the polyycarboxylic acid isadded in step (a) in an amount of equal to or greater than 0.01 weight%, based on the amount of starch. For this purpose, the weight of anywater present in the starch before step (a) is not taken into accountwhen calculating the ratio of polycarboxylic acid to starch. If morethan one polycarboxylic acid is added in step (a), the sum of weightpercentages of the more than one polycarboxylic acids is the same as theweight percentage denoted above for a single polycarboxylic acid.Preferably, the polycarboxylic acid is added in step (a) in an amount ofequal to or greater than 0.1 weight %. Most preferably, thepolycarboxylic acid is added in step (a) in an amount of equal to orgreater than 0.3 weight %. Generally, polycarboxylic acid is added instep (a) in an amount of equal to or less than 5 weight %. Preferably,the polycarboxylic acid is added in step (a) in an amount of equal to orless than 2.5 weight %. Most preferably, the polycarboxylic acid isadded in step (a) in an amount of equal to or less than 1 weight %. In amost preferred embodiment of this invention, the amount of thepolycarboxylic acid added in step (a) is from 0.35 to 0.9 weight %. Inthe present embodiment, the polycarboxylic acid is present incombination with a salt in step (a). The metal cation species of thesalt is preferably selected from groups 1, 2, 11 or 12 of the periodicsystem. Preferably, the salt cation is selected from the groupconsisting of Mg2+, K+, Zn2+, Na+, Li+, Cu2+ and Ca2+, wherein Mg2+ isespecially preferred. The anion species of the salt is selected fromanions derived from mineral acids or organic acids, wherein the anion ispreferably selected from the group consisting of sulfate, nitrate,chloride, carbonate, acetate and malonate. Especially preferred iscarbonate. A very preferred salt in this embodiment is MgSO⁴, anotherpreferred salt is MgCO³. According to the present invention, the salt isgenerally added in step (a) in an amount of equal to or greater than0.005 weight %, based on the amount of starch. For this purpose, theweight of any water present in the starch before step (a) is not takeninto account when calculating the ratio of salt to starch. If more thanone salt is added in step (a), the sum of weight percentages of the morethan one salts is the same as the weight percentage denoted above for asingle salt. Preferably, the salt is added in step (a) in an amount ofequal to or greater than 0.05 weight %. Most preferably, the salt isadded in step (a) in an amount of equal to or greater than 0.15 weight%. Generally, salt is added in step (a) in an amount of equal to or lessthan 2.5 weight %. Preferably, the salt is added in step (a) in anamount of equal to or less than 1.2 weight %. Most preferably, the saltis added in step (a) in an amount of equal to or less than 1 weight %.In a most preferred embodiment of this invention, the amount of the saltadded in step (a) is from 0.2 to 0.8 weight %.

According to another embodiment of the present invention, one or moreadditives from the second group are present in step (a), wherein the oneadditive or one of more than one additives is at least onehydroxycarboxylic acid. The hydroxycarboxylic acid present in step (a)is a hydroxycarboxylic acid which has from 2 to 12 carbon atoms whichare at least in one position substituted by at least one —OH-group.Preferably, the hydroxycarboxylic acid of step (a) is selected from thegroup consisting of lactic acid, glycolic acid and hydroxybutyric acid.Most preferably, the hydroxycarboxylic acid is lactic acid. Generally,more than one hydroxycarboxylic acid can be added in step (a). Thehydroxycarboxylic acid can be substituted, additionally to the at leastone substitution with —OH, with one or more substituents selected fromthe group comprising primary, secondary or tertiary amines, amides,nitro, nitrile, amido, mercapto, optionally substituted or unsubstitutedalkyl, optionally substituted or unsubstituted aryl, keto-group andaldehyde-group. In the case that the optionally substituted orunsubstituted hydroxycarboxylic acid has one or more stereocenters, theterm “hydroxycarboxylic acid” as used in the present invention includesall racemates, enantiomers, diastereomers or mixtures of any of theforegoing, as well as any hydroxycarboxylic acid which bears more thanone —OH-group or other substitutent. According to the present invention,the hydroxycarboxylic acid is added in step (a) in an amount of equal toor greater than 1 weight %, based on the amount of starch. For thispurpose, the weight of any water present in the starch before step (a)is not taken into account when calculating the ratio ofhydroxycarboxylic acid to starch. If more than one hydroxycarboxylicacid is added in step (a), the sum of weight percentages of the morethan one hydroxycarboxylic acids is the same as the weight percentagedenoted above for a single hydroxycarboxylic acid. Preferably, thehydroxycarboxylic acid is added in step (a) in an amount of equal to orgreater than 2 weight %. Most preferably, the hydroxycarboxylic acid isadded in step (a) in an amount of equal to or greater than 3 weight %.Generally, hydroxycarboxylic acid is added in step (a) in an amount ofequal to or less than 15 weight %. Preferably, the hydroxycarboxylicacid is added in step (a) in an amount of equal to or less than 12weight %. Most preferably, the hydroxycarboxylic acid is added in step(a) in an amount of equal to or less than 9 weight %. In a mostpreferred embodiment of this invention, the amount of thehydroxycarboxylic acid added in step (a) is from 3.5 to 8.5 weight %.

In another embodiment of the present invention, no additive from thesecond group of additives is present in step (a).

In one embodiment of the invention, step (a) and subsequent reactionsteps (b) (and (c), wherein applicable) are carried out in the presentof a carboxylic acid RC(O)OH. In this embodiment, the carboxylic acidRC(O)OH is added as reaction medium. Preferably, the acyl-group of thecarboxylic acid RC(O)OH corresponds to the acyl-group transferred by theacylating agent. More preferably, the acylating agent is a symmetricalcarboxylic acid anhydride of formula (RC(O))₂O and the carboxylic acidserving as reaction medium has the formula RC(O)OH, wherein R is definedas above, and RC(O) is the same in the carboxylic acid anhydride andcarboxylic acid that serves as reaction medium. Most preferably, theacylating agent is acetic acid anhydride, and the carboxylic acid whichserves as reaction medium is acetic acid. In this embodiment, generallythe amount by weight of RC(O)OH added in step (a) is approximately equalto the amount by weight of starch, subtracting the potentially presentmoisture in the starch from the amount of starch in the calculation.Preferably, the amount of RC(O)OH is equal to or greater than 80 weight%. More preferably, the amount of RC(O)OH is equal to or greater than 90weight %. Most preferably, the amount of RC(O)OH is equal to or greaterthan 95 weight %. Preferably, the amount of RC(O)OH is equal to or lessthan 120 weight %. More preferably, the amount of RC(O)OH is equal to orless than 110 weight %. Most preferably, the amount of RC(O)OH is equalto or less than 105 weight %. In a most preferred embodiment of thisinvention, the amount of RC(O)OH added in step (a) is from 95 to 105weight %. Generally, more than one carboxylic acid RC(O)OH can bepresent in step (a).

According to the present invention, the amount of water in the aqueousphase present in step (a) is generally equal to or greater than 5 weight%, based on the amount of starch. For this purpose, the weight of anywater present in the starch before step (a) is not taken into accountwhen calculating the ratio of salt to starch. Preferably, the amount ofwater is equal to or greater than 6 weight %. Most preferably, theamount of water is equal to or greater than 10 weight %. Generally, theamount of water in the aqueous phase present in step (a) is equal to orless than 30 weight %. Preferably, the amount of water is equal to orless than 25 weight %. Most preferably, the amount of water is equal toor less than 20 weight %. In a most preferred embodiment of theinvention, the amount of water in the aqueous phase present in step (a)is from 10% to 20%.

In an alternative embodiment of present invention, the amount of waterin the aqueous phase present in step (a) is generally equal to orgreater than 1 weight %, based on the amount of starch. For thispurpose, the weight of any water present in the starch before step (a)is not taken into account when calculating the ratio of salt to starch.Preferably, the amount of water is equal to or greater than 1.5 weight%. Most preferably, the amount of water is equal to or greater than 2weight %. Generally, the amount of water in the aqueous phase present instep (a) is equal to or less than 30 weight %. Preferably, the amount ofwater is equal to or less than 25 weight %. Most preferably, the amountof water is equal to or less than 20 weight %. In a most preferredembodiment of the invention, the amount of water in the aqueous phasepresent in step (a) is from 2% to 20%. According to the presentinvention, step (a) is generally carried out at a temperature equal toor greater than 20° C. Preferably, step (a) is carried out at atemperature equal to or greater than 40° C. Most preferably, step (a) iscarried out at a temperature equal to or greater than 60° C. Generally,step (a) is carried out at a temperature equal to or lower than 120° C.Preferably, step (a) is carried out at a temperature equal to or lowerthan 110° C. Most preferably, step (a) is carried out at a temperatureequal to or lower than 100° C.

In a most preferred embodiment of this invention, step (a) is carriedout at a temperature from 60 to 80° C.

In an alternative embodiment of this invention, step (a) is carried outat a temperature from 60 to 95° C.

According to the present invention, step (a) is generally carried outduring a reaction time of equal to or more than 1 minute. Preferably,step (a) is carried out during a time of equal to or more than 3minutes. Most preferably, step (a) is carried out during a time of equalto or more than 5 minutes. Generally, step (a) is carried during a timeof equal to or less than 8 hours. Preferably, step (a) is carried duringa time of equal to or less than 5 hours. Most preferably, step (a) iscarried during a time of equal to or less than 3 hours. In a mostpreferred embodiment of this invention, step (a) is carried carriedduring a time from 1 minute to 60 minutes.

In an alternatove embodiment of this invention, step (a) is carriedcarried during a time from 1 minute to 2 hours.

Notably the viscosity of the acylated polymer composition comprisingamylose and/or amylopectin is influenced by the choice of temperatureand reaction time in step (a). For high viscosity of the acylatedpolymer composition comprising amylose and/or amylopectin, lowertemperatures and/or shorter reaction times are selected. For lowviscosity, higher temperatures and/or longer reaction times areselected.

According to the present invention, the pre-treated polymer compositioncomprising amylose and/or amylopectin of step (a) is reacted with anacylating agent in step (b). As outlined above, an acylating agent isintended to denote a reactant which is capable of reacting with thehydroxylgroups of the glucose units of the starch, thereby transferringan acyl group —C(O)R, —C(O)R′ and/or −C(O)R″ to form the acylatedstarch. Acylation agents may be, for example, carboxylic acid anhydrides(RC(O))₂O, but also unsymmetrical carboxylic acid anhydridescorresponding to the formula (RC(O))(R″C(O))O. Other suitable acylatingagents comprise carboxylic acid halides or carbonylimidazoles.Generally, more than one acylating agent may be present in step (b).

This invention also relates to the formation of mixed acylated starch,where “mixed” is intended to denote more than one acylating agentpresent in the reaction, or a carboxylic acid R′C(O)OH is present in theacylation reaction with (R″C(O))₂O. In one embodiment, the acylation iscarried out with the acylating agent (R″C(O))₂O in the presence ofR′C(O)OH to give ST(OH)_(3-x-y)(OC(O)R′)_(x)(OC(O)R″)_(y). Again, DS(x+y) in the final product is usually from 2.0 to 2.9. R′ and R″ denoteindependently from another the same as R above.

In one embodiment, the acylating agent is an unsymmetrical carboxylicacid anhydride (RC(O))(R″C(O))O, wherein R is not identical with R″, andwherein mixed acylated starches are formed of the formulaST(OH)_(3-x-y)(OC(O)R′)_(x)(OC(O)R″)_(y) with a DS=(y+x), which isusually from 2.0 to 2.9 are formed in the final product, and wherein Rand R″ are defined as above.

In a preferred embodiment, symmetrical carboxylic acid anhydrides areused as acylating agent. More preferably, R in (RC(O))₂O is —C₂H₅,—CH₂CH₂F, —CH₂CHF₂ or —CH₂CF₃, meaning that the carboxylic acidanhydrides are selected from the group comprising acetic acid anhydride,difluoro acetic acid anhydride and trifluoro acetic acid anhydride. Mostpreferably, the acylating agent is acetic acid anhydride.

In the specification, the term “acylating agent” is intended to includethe term “one or more acylating agents”.

According to the present invention, the acylating agent is generallyadded in step (b) at a reaction temperature of equal to or greater than40° C. More preferably, the acylating agent is added in step (b) at areaction temperature of equal to or greater than 50° C. Most preferably,the acylating agent is added in step (b) at a reaction temperature ofequal to or greater than 60° C. Generally, the acylating agent is addedin step (b) at a reaction temperature of equal to or lesser than 100° C.More preferably, the acylating agent is added in step (b) at a reactiontemperature of equal to or greater than 90° C. Most preferably, theacylating agent is added in step (b) at a reaction temperature of equalto or greater than 80° C. In a most preferred embodiment, the acylatingagent is added in step (b) at a reaction temperature from 62 to 78° C.In order to control the temperature during the exothermic acylationstep, the acylating agent may be cooled before addition to the reactionmixture, for example to a temperature of from 3 to 10° C.

In an alternative embodiment according to the present invention, theacylating agent is generally added in step (b) at a reaction temperatureof equal to or greater than 40° C. More preferably, the acylating agentis added in step (b) at a reaction temperature of equal to or greaterthan 50° C. Most preferably, the acylating agent is added in step (b) ata reaction temperature of equal to or greater than 60° C. Generally, theacylating agent is added in step (b) at a reaction temperature of equalto or lesser than 100° C. More preferably, the acylating agent is addedin step (b) at a reaction temperature of equal to or greater than 98° C.Most preferably, the acylating agent is added in step (b) at a reactiontemperature of equal to or greater than 95° C. In a most preferredaspect, the acylating agent is added in step (b) at a reactiontemperature from 62 to 95° C.

According to the present invention, the reaction mixture in step (b)after the addition of the acylating agent is generally heated for equalto or longer than 10 minutes. More preferably, the mixture in step (b)after the addition of the acylating agent is heated for equal to orlonger than 20 minutes. Even more preferably, the mixture in step (b)after the addition of the acylating agent is heated for equal to orlonger than 30 minutes. Generally, the reaction mixture in step (b)after the addition of the acylating agent is heated for equal to or lessthan 5 hours. More preferably, the mixture in step (b) after theaddition of the acylating agent is heated for equal to or less than 4hours. Even more preferably, the mixture in step (b) after the additionof the acylating agent is heated for equal to or less than 3 hours. Theend point for the heating of the acylation reaction mixture in step (b)generally is indicated by complete or substantially complete dissolutionof the slurry formed initially in step (a), indicating a complete orsubstantially complete acylation of the hydroxylgroups in the starch toa DS of equal to or more than 2.8, preferably equal to or more than 2.9,in step (b). In a most preferred embodiment, the reaction time for theacylation reaction in step (b) is from 30 minutes to 3 hours.

In an alternative embodiment according to the present invention, thereaction mixture in step (b) after the addition of the acylating agentis generally heated for equal to or longer than 10 minutes. Morepreferably, the mixture in step (b) after the addition of the acylatingagent is heated for equal to or longer than 20 minutes. Even morepreferably, the mixture in step (b) after the addition of the acylatingagent is heated for equal to or longer than 30 minutes. Generally, thereaction mixture in step (b) after the addition of the acylating agentis heated for equal to or less than 6 hours. More preferably, themixture in step (b) after the addition of the acylating agent is heatedfor equal to or less than 5 hours. Even more preferably, the mixture instep (b) after the addition of the acylating agent is heated for equalto or less than 4 hours. The end point for the heating of the acylationreaction mixture in step (b) generally is indicated by complete orsubstantially complete dissolution of the slurry formed initially instep (a), indicating a complete or substantially complete acylation ofthe hydroxylgroups in the starch to a DS of equal to or more than 2.8,preferably equal to or more than 2.9, in step (b). In a most preferredaspect, the reaction time for the acylation reaction in step (b) is from30 minutes to 3.5 hours.

According to the present invention, the reaction temperature at whichthe reaction mixture is kept in step (b) after addition of the acylatingagent, is generally equal to or higher than 40° C. More preferably, thereaction temperature at which the reaction mixture is kept in step (b)after addition of the acylating agent, is equal to or higher than 50° C.Even more preferably, the reaction temperature at which the reactionmixture is kept in step (b) after addition of the acylating agent, isequal to or higher than 55° C. Generally, the reaction temperature atwhich the reaction mixture is kept in step (b) after addition of theacylating agent, is equal to or lower than 120° C. More preferably, thereaction temperature at which the reaction mixture is kept in step (b)after addition of the acylating agent, is equal to or lower than 110° C.Even more preferably, the reaction temperature at which the reactionmixture is kept in step (b) after addition of the acylating agent, isequal to or lower than 100° C. Most preferably, the reaction temperatureat which the reaction mixture is kept in step (b) after addition of theacylating agent, is from 60° C. to 90° C.

In an alternative aspect, the reaction temperature at which the reactionmixture is kept in step (b) after addition of the acylating agent isfrom 60° C. to 95° C.

In the specification, “amount of acylating agent” or “molar ratio ofpolymer composition comprising amylose and/or amylopectin to acylatingagent” also denotes the sum of amounts of acylating agents used in step(b), when more than one acylating agent is used.

According to the present invention, complete or substantially completeacylation of the polymer composition comprising amylose and/oramylopectin can be achieved in step (b), with a DS of equal to orgreater than 2.8, or, more preferably, 2.95. Accordingly, the molarratio of acetylating agent and polymer composition comprising amyloseand/or amylopectin is selected. For the calculation, the molar weight ofthe polymer composition comprising amylose and/or amylopectin isequalized with that of its repeating unit anhydroglucose. In the case ofunmodified polymer composition comprising amylose and/or amylopectin,each mole of anhydroglucose bears basically three free hydroxylgroupswhich are acylated. Generally, the molar ratio of acylating agent topolymer composition comprising amylose and/or amylopectin in step (b) isequal to or higher than 3:1. Preferably, the molar ratio of acylatingagent to polymer composition comprising amylose and/or amylopectin instep (b) equal to or higher than 4:1. Even more preferably, the molarratio acylating agent to polymer composition comprising amylose and/oramylopectin in step (b) equal to or higher than 4.5:1. According to thepresent invention, the molar ratio of acylating agent to polymercomposition comprising amylose and/or amylopectin in step (b) equal toor lower than 19:1. Preferably, the molar ratio of polymer compositioncomprising amylose and/or amylopectin to acylating agent in step (b)equal to or lower than 1:8. Even more preferably, the molar ratio ofacylating agent to polymer composition comprising amylose and/oramylopectin in step (b) equal to or lower than 7:1. Most preferably, themolar ratio of acylating agent to polymer composition comprising amyloseand/or amylopectin is from 4:1 to 5.5:1.

Additional acylating agent may be present in step (b) corresponding tothe amount of water present, and such excess of acylating agent isselected accordingly in addition to the molar ratio respective to thepolymer composition comprising amylose and/or amylopectin.

According to the present invention, after completed acylation reactionin step (b), which is indicated by complete or substantially completedissolution of the reactants, the reaction mixture of step (b) issuitably a cooled to a temperature of from 40° C. to 70° C. Morepreferably, the reaction mixture is cooled to a temperature of from 45°C. to 65° C. To the reaction mixture, suitably, a solution of carboxylicacid RC(O)OH, wherein the acyl residue of the carboxylic acidcorresponds to at least one acyl residue of the at least one acylatingagent of step (b), in water is added. By this, any excess of theacylating agent is converted into its corresponding carboxylic acid.

Generally, the DS of the acylated polymer composition comprising amyloseand/or amylopectin as obtained by consecutive steps (a) and (b) is equalto or greater than 2.8, and often greater than 2.95. It has been found,surprisingly, that the treatment of the acylated polymer compositioncomprising amylose and/or amylopectin obtained by consecutive steps (a)and (b) with an acid A′ in a step (c) in order to obtain an acylatedpolymer composition comprising amylose and/or amylopectin with a DS offrom 2.0 to 2.9 has beneficial impact on the solubility of the acylatedpolymer composition comprising amylose and/or amylopectin. Such anacylated polymer composition comprising amylose and/or amylopectindisplays a good solubility in a large variety of aprotic solvents suchas esters, while simultaneously having a high EtOH tolerance. This is anunexpected characteristic of the acylated polymer composition comprisingamylose and/or amylopectin obtainable by consecutive steps (a), (b) and(c), which cannot be achieved by e.g. partial acylation in step (b).

Consequently, according to a preferred embodiment of the presentinvention, the acylated polymer composition comprising amylose and/oramylopectin in the reaction mixture of consecutive steps (a) and (b) isthus reacted with at least one acid A′ in step (c). In thespecification, “acid A′” is intended to denote also “at least one acidA′”, including more than one acids A′. Acid A′ is defined to be an acidhaving a pKa of equal to or less than 4.8 at 25° C. Generally, the acidA′ having a pKa of equal to or less than 4.8 at 25° C. is selected fromthe group consisting of mineral acids, sulfonic acids and carboxylicacids. Acid A′ can be either monoprotic or polyprotic. If acid A′ ispolyprotic, at least pKa₁ is equal to or less than 4.8 at 25° C.Preferably, acid A′ is selected from the group consisting of sulfuricacid, amidosulfonic acid, methane sulfonic acid, benzene sulfonic acidor phosphoric acid. Most preferably, acid A′ is selected from the groupconsisting of sulfuric acid and benzene sulfonic acid. Generally, morethan one acid A′ can be added in step (c).

According to the present invention, the acid A′ in step (c) is added tothe reaction mixture at a temperature of equal to or higher than 40° C.Preferably, the acid A′ in step (c) is added to the reaction mixture ata temperature of equal to or higher than 50° C. Even more preferably,the acid A′ in step (c) is added to the reaction mixture at atemperature of equal to or higher than 60° C. Generally, the acid A′ instep (c) is added to the reaction mixture at a temperature of equal toor lower than 100° C. Preferably, the acid A′ in step (c) is added tothe reaction mixture at a temperature of equal to or lower than 98° C.Even more preferably, the acid A′ in step (c) is added to the reactionmixture at a temperature of equal to or lower than 95° C. In a mostpreferred embodiment, the acid A′ in step (c) is added to the reactionmixture at a temperature of from 65° C. to 95° C.

According to the present invention, acid A′ is added in step (c) in anamount of equal to or greater than 0.002 weight %, based on the amountof polymer composition comprising amylose and/or amylopectin provided tostep (a). For this purpose, the weight of any moisture present in thepolymer composition comprising amylose and/or amylopectin before step(a) is not taken into account when calculating the ratio of acid topolymer composition comprising amylose and/or amylopectin. If more thanone acid A′ is added in step (c), the sum of weight percentages of themore than one acids A′ is the same as the weight percentage denoted inthe specification for a single acid A′. Preferably, acid A′ is added instep (c) in an amount of equal to or greater than 0.01 weight %. Mostpreferably, acid A′ is added in step (c) in an amount of equal to orgreater than 0.1 weight %. Generally, acid A′ is added in step (c) in anamount of equal to or less than 5 weight %. Preferably, acid A′ is addedin step (c) in an amount of equal to or less than 2 weight %. Mostpreferably, acid A′ is added in step (c) in an amount of equal to orless than 1 weight %. In a most preferred embodiment of this invention,the amount of acid A′ added in step (c) is from 0.2 to 0.8 weight %.After addition of acid A′, the reaction mixture is kept at the additiontemperature as defined above, for a time defined below as “post additionheating time”.

The post-addition heating time in step (c) is selected according to theintended DS of the final acylated polymer composition comprising amyloseand/or amylopectin. Longer post-addition heating times will result inlower

DS values. Generally, the post-addition heating time is equal to orlonger than 10 minutes. Preferably, the post-addition heating time isequal to or longer than 20 minutes. Even more preferably, thepost-addition heating time is equal to or longer than 30 minutes.According to the present invention, the post-addition heating time isequal to or less than 10 hours. Preferably, the post-addition heatingtime is equal to or less than 9 hours. Even more preferably, thepost-addition heating time is equal to or less than 8 hours. In a mostpreferred embodiment, the post-addition heating time is from 50 minutesto 6 hours.

In step (c), the reaction time, temperature and amount of A′ is selectedsuch that the DS of the final product is equal to or higher than 2.05.Preferably, the DS after step (c) is equal to or higher than 2.08. Evenmore preferably, the DS after step (c) is equal to or higher than 2.1.According to the present invention, the DS after step (c) is equal to orlower than 2.9. Preferably, the DS after step (c) is equal to or lowerthan 2.6. Even more preferably, the DS after step (c) is equal to orlower than 2.5. In a most preferred embodiment, the DS after step (c) isfrom 2.1 to 2.4.

It should be noted that the total amount of water present in thereaction mixture before the addition of acid A′ in step (c) ispreferably from 5 to 20%, and should suitably be adjusted accordingly ifnot already achieved.

According to the present invention, the acylated product is recoveredafter step (c) by precipitation in water. Further isolation steps maycomprise e.g. washing, filtering, spinning, pressing, drying and/ormilling.

In one embodiment of the present invention, any of the steps (a), (b)and (c) individually or in any combination may be performed in thepresence of additional solvents, reactants or reagents, such as organicsolvents like dichloromethane or toluene.

According to another embodiment, at any time during the processaccording to the present invention, solvents, reactants or reagents arerecovered from the process for further use.

The pKa value, known as acid dissociation constant, of acid A may bedetermined by standard potentiometric titration procedure.Alternatively, NMR or UV determination methods can be employed for pKadetermination.

The DS value is measured by the following method. The acylated polymeris reacted with sulfuric acid for a time of from 15 to 30 hours at atemperature of from 18 to 23° C. The reaction mixture is subjected to asteam distillation, preferably in an automated distillation apparaturssuch as Vadopest 40s (Gerhardt Analytical Systems). The distillate istitrated with NaOH. The DS can be calculated from the amount of NaOHwhich is needed to neutralize the distillate.

The EtOH tolerance is a solubility parameter. It describes the amount ofethanol which is necessary to precipitate a defined amount of a product,in this case the acylated starch, from a solution of a definedconcentration in which the acylated starch is completely dissolved,preferably a solution in an aprotic solvent such as ethyl acetate. Thehigher the EtOH tolerance, the higher the tolerance of the producttowards a protic solvent in the presence of an aprotic solvent.Generally, acylated starches are either soluble in protic or aproticsolvents. It has been found, surprisingly, that the acylated starchesobtained by the process according to the present invention display agood solubility towards aprotic solvents while simultaneously toleratingprotic solvents. This makes the acylated starches according to thepresent invention very suitable for use in inks, varnishes, lacquers,coatings, thickeners, adhesives or binders, which all use a largevariety of different solvent systems.

EtOH Tolerance is measured in a turbidity titration using a T70Titration Excellence Line of Mettler Toledo with a DP5-Phototrode.

For the titration a 10% solution of acylated polymer compositioncomprising amylose and/or amylopectin in EtOAc is prepared, and a sampleof 25 mL of this 10% solution in EtOAc is automatically titrated withEtOH at 25° C.

For acylated polymer compositions comprising amylose and/or amylopectinwith a DS from 2.1 to 2.45, the end point of the titration is a solidcontent of precipitated acylated polymer composition comprising amyloseand/or amylopectin between 3.3% to 4.7%. The EtOH tolerance in this DSrange for the acylated polymer comprising amylose and/or amylopectinaccording to the present invention is from 53 (v/v) to 63% (v/v). Thisdenotes that 33% to 4-7% of the acylated polymer precipitates in asolution of from 53% (v/v) of EtOH in EtOAc to 63% (v/v) of EtOH inEtOAc. This also relates to the EtOH-dilutibility of the acylatedpolymer, which is further described below. The EtOH dilutibility in theDS range from 2.1 to 2.45 for the acylated polymer comprising amyloseand/or amylopectin according to the present invention is from 1.12 to1.7.

For acylated polymer compositions comprising amylose and/or amylopectinwith a DS from 2.46 to 2.9, the end point of the titration is a solidcontent of precipitated acylated starch between 4% to 9.5%. The EtOHtolerance in this DS range is equal to or lower than 60% (v/v).Preferably, the EtOH tolerance in this DS range is from 5% (v/v) to 57%(v/v). This also relates to the EtOH-dilutibility of the acylatedpolymer, which is further described below. The EtOH dilutibility in theDS range from 2.46 to 2.9 for the acylated polymer comprising amyloseand/or amylopectin according to the present invention is equal to orlower than 1.5. Preferably, the EtOH dilutibility in this DS range isfrom 0.05 to 1.33.

The EtOH tolerance is an alternative way to describe the“non-solvent-dilutibility”, here EtOH dilutibility, of the acylatedcompositions comprising amylose and/or amylopectin in a solvent in whichthe polymer can be well solved, which is in this case EtOAc. A solutionconsisting of acylated polymer and EtOAc is titrated against a polarsolvent, often water, but in the present invention EtOH, which will notsolve the polymer and is the non-solvent. The polymer compositioncomprising amylose and/or amylopectin in EtOAc is titrated against EtOHuntil turbidity is observed as described above, indicating flocculationof polymer precipitating out of the titrated polymer composition inEtOAc. The non-solvent-dilutibility is a term known is the literature,e.g. in J. Prieto and J. Kiene, “Holzbeschichtung”, p. 61, 2007,published by Vincentz Network GmbH (ISBN 3-87870-749-5) where it isidentified by the german term “Verschneidbarkeit”, which is defined asthe amount of non-solvent, in the present invention EtOH, which can beadded to a solution of polymer in an amount of solvent, which is EtOAcin the present invention, until gelatinization or flocculation isobserved. For example, a dilutibility of 1.12 indicates that up to 1.12parts of EtOH can be added to the solution containing acylated polymercomprising amylose and/or amylopectin and 1 part EtOAc untilprecipitation is observed. The dilutibility as used in the presentinvention not only indicates the suitability of the solvent for a givenpolymer, but, for a given non-solvent/solvent system at a givenconcentration and temperature, also the tolerance of a polymer againstthe non-solvent in its solvent. This characteristic not only related tothe DS of a polymer composition comprising amylose and/or amylopectin,but presumably is also directly dependent on the substitution pattern ofthe hydroxyl-group of the polymer composition, which is effectivelycontrolled in the process according to the present invention.

The viscosity of a fluid is a measure of its resistance to gradualdeformation by shear stress or tensile stress. For liquids, itcorresponds to the informal notion of “thickness”. Solutions of anacylated polymer composition comprising amylose and/or amylopectin canalso be characterized by their viscosity, which is mainly dependent onthe physical and chemical properties of the acylated polymer compositioncomprising amylose and/or amylopectin, when viscosities of the sameconcentration, in the same solvent and at the same temperature arecompared. It has been found, surprisingly, that the viscosity of theacylated polymer composition comprising amylose and/or amylopectinaccording to the present invention can be influenced in a desirablerange by setting reaction parameters accordingly, notably the parametersof step (a). This makes the acylated polymer composition comprisingamylose and/or amylopectin according to the present invention verysuitable for use in inks, varnishes, lacquers, coatings, thickeners,adhesives or binders, which all use a large variety of different solventsystems and have various specific viscosity requirements in thosesolvent systems.

The acylated polymer composition comprising amylose and/or amylopectinobtainable by the process according to the present invention possess aviscosity, measured in a 35% (w/w) solution in EtOAc at 25° C. with arotational viscosimeter, such as Rheomat R180 (ProRheo), of from 10-200mPas. Preferably, the viscosity is equal to or larger than 10 mPas. Evenmore preferably, viscosity is equal to or larger than 12 mPas.Preferably, the viscosity is equal to or less than 200 mPas. Even morepreferably, viscosity is equal to or less than 190 mPas. In a mostpreferred embodiment, the viscosity if from 15 to 180 mPas.

If the combination of at least one salt and at least one polycyboxylicacid is selected from the second group of additives in step (a), it ispreferred that the viscosity of the acylated product is less than 77mPas, measured as a 10 w % solution in Triacetin at 30° C.

If at least one hydroxycarboxylic acid is selected from the second groupof additives in step (a), it is preferred that the viscosity of theacylated product is less than 50 mPas, measured as a 10 w % solution inTriacetin at 30° C.

According to one preferred aspect, the process according to the presentinvention is carried out in a continuous mode. In another aspect, it canbe advantageous to operate one or more steps of the present invention ina batch-wise mode. Should the disclosure of any patents, patentapplications, and publications which are incorporated herein byreference conflict with the description of the present application tothe extent that it may render a term unclear, the present descriptionshall take precedence.

EXAMPLES Example 1

1000 kg of waxy maize with a moisture content of 12.6 weight % werereacted with 900 kg of glacial acetic acid, 2.2 kg of sulphuric acid(72% w/w) and 20 kg of distilled H₂O for 1.5 h between 75-95° C.

3250 kg of acetic anhydride (91.2% w/w, T=8° C.) were added in portions1.5 h.

The reaction temperature was kept between 75 and 95° C.

After 3.5 h the reactants and product were completely dissolved. Thereaction mixture was cooled down to 50° C. and 365 kg of 40% w/w aceticacid in water were added. Afterwards the reaction mixture wasprecipitated in water to obtain the acetylated starch.

The precipitated powder was washed until no acetic acid was detectable.

The starch acetate powder was pressed of to a solid content of approx.20 weight % and dried to a moisture content of approx. 0.5-3 weight %.

Example 2

In example 1, after the acetylation reaction was stopped by addition of40% acetic acid w/w in water, by which the water content of 8-12 weight% was adjusted in the reaction mixture. The reaction mixture was heatedup until a temperature of between approx. 70-95° C. and 03 weight % ofconcentrated sulphuric acid (95-98% w/w) was added.

In 1-17 h at 70-95° C. a series of different DS (2.9-2.2) was obtained.The products were soluble in ethylacetate, butylacetate, cyclohexanone,acetone, triacetine, chloroform, depending of the degree ofsubstitution.

The characteristics of the starch acetate obtained after 13 h were asfollowing:

Viscosity (35 weight % in ethylacetate, 25° C.): 75 mPas;

The solid composition of this particular derivative with a DS of 2.26has an average density of 1.37 g/cm³, a surface area of 9.5 m²/g, a bulkdensity of 0.283, a main partical size distrubtion of 10-100 μm and aglass transition offset temperature of 151.28° C.

Example 3

450 g of waxy maize with a moisture content of 13.6 weight % werereacted with 420 g of glacial acetic acid, 1.1 g of sulphuric acid (72%w/w) and 4 g of distilled H₂O for 1.0 h at 75° C.

1.45 kg of acetic anhydride (91.2% w/w, T=8° C.) were added continuouslythrough a pump within 3.5 h.

The reaction temperature was kept between 75 and 95° C.

After 3.5 h the reactants and product were completely dissolved. Thereaction mixture was cooled down to 50° C. and 0.220 l of 56.5% w/wacetic acid in water were added. After the reaction was stopped byaddition of 56.5% w/w acetic acid, a water content of 10-12 weight % wasadjusted in the reaction mixture, the reaction mixture was heated up toa temperature between approx. 70-95° C. and 0.002 weight % ofconcentrated sulphuric acid (95-98% w/w) is added.

In 1-10 h a series of different DS (substitution degree 2.9-1.6) wasobtained.

The precipitated powder was washed until no acetic acid was detectable.

The starch acetate powder was pressed of to a solid content of approx.20 weight % and dried to a moisture content of approx. 0.5-3 weight %.Viscosity (35 w % in EtOAc at 25° C.)=28 mPas (after 4.5 hours oftreatment according to step c))

Soluble in ethylacetate, triacetine, chloroform.

1-17. (canceled)
 18. A process for the manufacture of an acylatedpolymer composition comprising amylose and/or amylopectin, having aviscosity from between 10 to 200 mPas (35 w % in EtOAc at 25° C.), whichcomprises: (a) pre-treating a polymer composition comprising amyloseand/or amylopectin with an aqueous phase comprising one additiveselected from the group consisting of at least one acid A having a pKaof equal to or less than 4.8 at 25° C. and an enzyme, and optionally oneor more additives selected from the group comprising at least one saltin combination with at least one polycarboxylic acid, and at least onehydroxycarboxylic acid; and (b) reacting the pre-treated polymercomposition with an acylating agent to provide an acylated polymercomposition comprising amylose and/or amylopectin.
 19. A process for themanufacture of an acylated polymer composition comprising amylose and/oramylopectin, having a viscosity from between 10 to 200 mPas (35 w % inEtOAc at 25° C.), which comprises: (a) pre-treating a polymercomposition comprising amylose and/or amylopectin with an aqueous phasecomprising one additive selected from the group consisting of at leastone acid A having a pKa of equal to or less than 4.8 at 25° C. and anenzyme, and optionally one or more additives selected from the groupcomprising at least one salt in combination with at least onepolycarboxylic acid, and at least one hydroxycarboxylic acid; (b)reacting the pre-treated polymer composition with an acylating agent toprovide an acylated polymer composition comprising amylose and/oramylopectin; and (c) reacting the acylated polymer composition obtainedin step (b) with at least one acid A′ with a pKa of equal to or lessthan 4.8 at 25° C., in the presence of water.
 20. The process of claim18, wherein in step (a) the polymer composition comprising amyloseand/or amylopectin is pre-treated at a temperature in a range of from20° C. to 85° C. during a pre-treatment time in a range of from 1minutes to 60 minutes.
 21. The process according to claim 19, whereinthe at least one acid A used in step (a) and the at least one acid A′used in step (c) can be the same or different and are selected from thegroup consisting of mineral acids, sulfonic acids, and carboxylic acids,all of which are either monoprotic or polyprotic.
 22. The processaccording to claim 18, wherein at least one additive is at least onesalt in combination with at least one polycarboxylic acid, wherein theat least one polycarboxylic acid has from 2 to 12 carbon atoms, and atleast two carboxylic acid groups —COOH.
 23. The process according toclaim 18, wherein at least one additive is at least onehydroxycarboxylic acid, wherein the least one hydroxycarboxylic acid hasfrom 2 to 12 carbon atoms which are at least in one position substitutedby at least one —OH-group.
 24. The process according to claim 18,wherein the additive is an enzyme, and wherein acid A′ in step (b) isselected from the group consisting of mineral acids, sulfonic acids, andcarboxylic acids, all of which are either monoprotic or polyprotic. 25.The process according to claim 18, wherein no additive is selected instep (a).
 26. The process according to claim 18, wherein the acylatingagent is selected from the group consisting of carboxylic acids,symmetrical or unsymmetrical carboxylic acid anhydrides, carboxylic acidhalides, and carboxylic acid carbonylimidazoles.
 27. The processaccording to claim 18, wherein step (a) is carried out in the presenceof a monocarboxylic acid, wherein the monocarboxylic acid corresponds tothe carboxylic acid obtained by hydrolysis of the acylating agent. 28.The process according to claim 18, wherein the polymer compositioncomprising amylose and/or amylopectin provided in step (a) is selectedfrom the group consisting of chemically modified starches, unmodifiedstarches, and a mixture of chemically modified starches and unmodifiedstarches, and wherein the chemically unmodified starch is selected fromthe group consisting of maize starch, wheat starch, potato starch, ricestarch, pea starch, rye starch, millet starch, and manioc starch, andwherein the chemically modified starch is selected from the groupconsisting of chemically modified maize starch, chemically modifiedwheat starch, chemically modified potato starch, chemically modifiedrice starch, chemically modified pea, chemically modified rye starch,chemically modified millet starch, and chemically modified maniocstarch.
 29. The process according to claim 28, wherein the chemicallymodified starch is selected from the group consisting of crosslinkedstarches, acylated starches, hydroxyethylated starches,hydroxypropylated starches, methylated starches, oxidized starches, andcationic or anionic starches.
 30. The process according to claim 18,wherein the time and temperature of the pre-treatment are selected suchthat the viscosity of the final acylated polymer composition comprisingamylose and/or amylopectin (measured as 35 w % solution in EtOAc at 25°C.) is in a range of from 10 to 200 mPas.
 31. The process according toclaim 19, wherein the reaction time and reaction temperature of step (c)is selected such that the degree of substitution (DS) of the acylatedpolymer composition comprising amylose and/or amylopectin is frombetween 2.0 to 2.9.
 32. An acylated polymer composition comprisingamylose and/or amylopectin, having a viscosity of from 10 to 200 mPas(35 weight % in EtOAc at 25° C.), which is made by a process comprisingthe following steps: (a) pre-treating a polymer composition comprisingamylose and/or amylopectin with an aqueous phase comprising one additiveselected from the group consisting of at least one acid A having a pKaof equal to or less than 4.8 at 25° C. and an enzyme, and optionally oneor more additives selected from the group comprising at least one saltin combination with at least one polycarboxylic acid, and at least onehydroxycarboxylic acid; (b) reacting the pre-treated polymer compositionwith an acylating agent to provide an acylated polymer compositioncomprising amylose and/or amylopectin; and (c) reacting the acylatedpolymer composition obtained in step (b) with at least one acid A′ witha pKa of equal to or less than 4.8 at 25° C., in the presence of water.33. An acylated polymer composition comprising amylose and/oramylopectin, having a degree of substitution (DS) in the range of from2.0 to 2.9, a viscosity of from 10 to 200 mPas (35 weight % in EtOAc at25° C.) and which has an EtOH tolerance of equal to or lower than 60%(v/v).
 34. A process of manufacturing inks comprising the acylatedpolymer composition comprising amylose and/or amylopectin of claim 32 asan ingredient in the process.
 35. The process according to claim 21,wherein the at least one acid A and the at least one acid A′ are thesame or different, and are selected from the group consisting ofsulfuric acid, amidosulfonic acid, benzene sulfonic acid, or phosphoricacid.
 36. The process according to claim 22, wherein the at least onepolycarboxylic acid is selected from the group consisting of oxalicacid, malonic acid and succinic acid, glutaric acid, and adipic acid.37. The process according to claim 22, wherein the at least one saltconsists of a metal cation species and an inorganic or organic anionspecies, wherein the metal cation species is selected from the groupconsisting of Mg²⁺, K⁺, Zn²⁺, Na⁺, Li⁺, Cu²⁺, and Ca²⁺, and the anionspecies is selected from the group consisting of sulfate, nitrate,chloride, carbonate, acetate, and malonate.
 38. The process according toclaim 23, wherein the at least one hydroxycarboxylic acid is selectedfrom the group consisting of lactic acid, glycolic acid, andhydroxybutyric acid.
 39. The process according to claim 24, wherein theenzyme is an amylase.
 40. The process according to claim 26, wherein thecarboxylic acid anhydride is acetic acid anhydride.